On Fri, Aug 24, 2012 at 12:09 AM, Chris Smith <[email protected]> wrote:
> With the aid of a manipulable dodecahedron I was able to construct the
> permutation group. All pgroups of the polyhedra are now included in
> Polyhedron. Thanks for the encouragement.
>
> I added a lot to the documentation with hopes of it being useful to
> someone that is about as initiated as I was at the beginning of the
> work on Saptarshi's combinatorics branch.
>
> Would you have any time to look over the changes that have been made
> at https://github.com/sympy/sympy/pull/1508?
>
To start, it is great that you are implementing this. Very interesting code
and useful and very tedious to work out, so *thanks very much" for that.
I only looked at the diff, and haven't tried downloading and running
your patch yet.
A few comments.
First, you say
" Although only 2 permutations are needed for a polyhedron in order to
generate all the possible orientations, it is customary to give a
group of permutations (P0, P1, ...) such that powers of them alone are
able to generate the orientations, e.g. P0, P0**2, P0**3, P1, P1**2,
etc..., instead of mixed permutations (P0*P1**2*P0). The following
work was used to calculate the permutation group of the polyhedra."
What does this mean? Why is it customary to give a "group" (you
mean "set" or "collection" I guess?) of perms s.t. powers alone generate
the "orientations" (I guess you mean "group elements" I guess?)?
I don't understand what this means.
I was also confused at first what "0-based" and "1-based" cycle notation
meant. I figured it out (or think I did) from the context and your examples,
but others might find it confusing. Just FYI.
Second, you say you give tests but no where do I see you say
"the permutation group representation of the symmetry group
of the cube is isomorphic to S_4" and test that the group you
generate has 24 elements. Am I missing something?
Similarly, I did not see "the permutation group representation
of the symmetry group of the dodecahedron is isomrphic to A_5"
and test that it has 60 elements.
If you don't do this, I don't see how you can be sure it is correct.
> --
> You received this message because you are subscribed to the Google Groups
> "sympy" group.
> To post to this group, send email to [email protected].
> To unsubscribe from this group, send email to
> [email protected].
> For more options, visit this group at
> http://groups.google.com/group/sympy?hl=en.
>
--
You received this message because you are subscribed to the Google Groups
"sympy" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sympy?hl=en.
